In recent years, as kinds of wireless communication services, such as W-CDMA, CDMA2000, and WiBro, that a user can select, becomes various, mobile communication terminals that support a multi communication mode have been developed. For example, a DBDM (Dual Band Dual Mode) terminal or a triple mode terminal in terms of hardware, or an SDR (Software Defined Radio) terminal in terms of software, which support two or more communication modes using single terminal, have been developed.
In order to access a wireless communication service using a mobile communication terminal that supports multi communication modes, a user needs to confirm communication modes that are available at a current location. An elementary and certain method that can be used at this time is to actually measure the strength of a radio wave for each of communication modes supported by the mobile communication terminal at the current location and select the most excellent communication mode.
This method that measures the strength of a radio wave for each of the communication mode is most safe. However, the direct measurement of the strength of a radio wave incurs extra power consumption in mobile terminal. Hence its constant use cannot be impractical in mobile terminal mainly due to battery limitation of the mobile terminal as well as mobile characteristics of the terminal.
Further, the received radio wave strength of the mobile communication terminal at a specific location is constant as long as a communication infra such as a base station and a repeater, and geomorphological configuration are not changed.
Thus, the following is required. A communication mode guide database where communication modes that can be supported for geographical coordinates and related information are organized is constructed in a communication mode guide data server. When a mobile communication terminal moves and the available communication modes are changed, the communication mode guide data server receives an available communication mode guide data request from the mobile communication terminal and provides, to the mobile communication terminal, available communication mode guide data at the current location, or the expected movement region of the mobile communication terminal. Then the mobile terminal can discover the available communication modes at the current location or the expected movable region without powerconsuming direct measurement of all available radio waves.
However, when a user who possesses a mobile terminal supporting multi communication modes moves to other regions through walking or transporting means such as a vehicle or a railroad, the available communication modes change. At this time, without communication mode guide data in the mobile terminal, the following problem occurs. The mobile terminal should continuously monitor all available communication modes while measuring the intensity of radio waves with respect to frequencies in all available communication modes.